Signaling system



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sIGNALIN SYSTEM Filed June 20, 1941 4 Sheets-Sheet 2 'OVRIGIIVATING MARKER FIG. 2

SELIECTIOR INVENTOR Wh'. 7THOLDEN WWK L A TTORNEV Dec. 29, 1942. w. H. T. HOLDEN SIGNALING SYSTEM s t e e h A h. I S h a W m v u u m mew UH HU M 4 H E 8m L a w L Pl L Pl e H m L m L F F mom INVENTOR um moms/v A TTORNE) Dec. 29, 1942. w. H. T. HOLDEN S IGNALING SYSTEM 4 Sheets-Sheet 4 Filed June 20, 1941 Hl- HI'IIWH IIWIU HI ill HllllJ INVENTOR WHT HOLDEN .ATTjA EV E Patented Dec. 29, 1942 SIGNALING SYSTEM William H. T. Holden, Woodside, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 20, 1941, Serial No. 398,887

10 Claims.

This invention relates to signaling systems and particularly to systems in which a multiplicity of signals are transmitted over a single transmission line.

The objects of the invention are to facilitate the identification of lines or other circuits; to prevent the associated identifying equipment from causing electrical disturbances in said lines or other circuits; to effect the operative association of the identifying equipment with a desired line by means of space discharge tubes when the identification is to be performed; to isolate said equipment from the line at all other times; and to obtain other improvements and advantages in signaling systems of this character.

The foregoing objects are realized by means of a system in which a signal impulse transmitter, common to a plurality of subscribers lines in a telephone office, is arranged to generate a multiplicity of impulses of a given polarity and of different phases. These impulses are applied to the sleeve conductor of the line to be identified through the multiple electrodes of a space discharge tube, said tube having a common electrode which is connected directly to the sleeve conductor of the line. If, for example, the line has a four-digit number, four multiple electrodes are provided in the discharge tube, and four impulse leads carrying impulses of difierent phases are connected to these multiple electrodes. providing each line with one of these discharge tubes and by connecting the phase impulse leads in different combinations of four to the multiple electrodes of the line tubes it is possible to deliver to the sleeve conductor and to each line a combination of four phase impulses which distinguishes that line from all other lines in the oifice. The impulses thus supplied to the sleeve conductor are transmitted through the switches involved in the connection to a receiving mechanism, which includes a plurality of discharge tubes having control electrodes to which the incoming impulses are applied. At the same time impulses of opposite polarity and of various phases are applied to the Thus by 1? other control electrodes of these receiving discharge tubes. The particular tubes having impulses of like phase applied to their electrodes operate to register the designation of the subscribers line involved in the connection. The

registered designation may then be used to control 53'?) the printing of a ticket to charge for the call being made or for any other purpose.

A feature of the invention is a system of this character in Which a common register sender,

serving to receive the digit impulses transmitted 5-5 from the calling subscriber's substation to characterize the called line, is provided with circuit controlling means for establishing the calling line identification circuit at some suitable time during the dialing operation. For instance, the sender may be designed to close the impulse identification circuit over the sleeve conductor through the operated switches to the electrode of the identification tube individual to the calling line as soon as the calling subscriber has transmitted the first digit of the called number. The closure of this circuit results in the ionization of the individual tube and the transmission therethrough from the multiplex impulse generator of a combination of four impulses of phases representing the calling line number. These impulses are transmitted through the common register sender to an identification mechanism where they are impressed upon the electrodes of receiving tubes, causing these tubes to operate in a combination representing the calling subscribers line number.

One of theadvantages of this invention is that the impulse generator, which is continuously producing impulses of a multiplicity of phases, is effectively isolated from the sleeve conductors of the subscribers lines, except for the brief interval during which any particular line is undergoing identification. This isolation is accomplished by means of the individual space discharge tubes.

These and other features of the invention will be described more fully in the following specification.

In the drawings accompanying the specification:

Figs. -1 to 4, when arranged in the order shown in Fig. 5, illustrate a portion of an automatic telephone system incorporating the features of the present invention.

Fig. 1 shows the subscribers lines entering the telephone oifice together with the impulse sending mechanism for sending impulses identifying these lines;

Fig. 2 shows the automatic switches for establishing connections. This figure also illustrates the sender selector and a switch-controlling marker;

Fig. 3 illustrates a portion of a central office register sender together with a connector for connecting the sender to the calling line identifying mechanism; and

Fig. 4 shows the calling line identifying mechanism.

The present invention is particularly useful in systems in which tickets are prepared for the purpose of assessing the calling subscriber for each conversation held with other subscribers. Since these tickets are prepared automatically it is necessary to determine the number of the calling line in order that the charge be assessed against the proper party. However, the invention may be used in any type of system where it is desirable to determine automatically the identity of a line, trunk or other circuit. For example, it is often desirable to display the number of the calling party before the operator to whom the line has been extended, eliminating the necessity of the operator making an oral request or performing a number checking operation.

Referring particularly to the drawings, subscribers lines I00 and IBI are shown appearing in primary line switch 203. The line switch 209 serves to extend a line when calling over a link circuit 22H and through to the secondary line switch 282 which serves to further extend the line over an idle trunk or junctor 203 to a first or district selector switch 204. In addition to being extended to a district selector 204, the calling line is also extended automatically by a sender selector switch 265 to an idle register sender 398. The register sender 308 receives the digit impulses transmitted from the calling subscribers dial and registers the designation of the called line. After receiving this designation, the sender 308 associates itself through a connector 266 with an idle marker 20?. The marker 201, after receiving the required information from the sender 309, connects itself, by means of frame connectors 208 and 209 with the district selector switch 204 and also with the next or office selector switch 2H2. The marker controls the district and ofiice switches to extend the calling line to an idle trunk 2II. Thereafter the connection is completed to the called subscriber's line, which may i ister sender at some suitable time during the 5';

progress of the call. Preferably these identifying signals are transmitted during the dialing operation, at which time they are less likely to produce interference. The impulse transmitting mechanism for sending the identifying signals includes an impulse generator I02 which is designed to produce voltages of a multiplicity of phases and to apply these voltages to a corresponding number of output circuits. Although the number of output circuits from the generator I82 may be varied at will, forty of these output circuits are illustrated on the assumption that the subscribers line numbers have four digital places. The first ten output circuits I03, on which voltages of the first ten phases appear, represent the ten different values of the thousands digit. Similarly, the second, third and fourth groups of ten output conductors I04, I05 and IE6, on which voltages of the corresponding phases appear, represent respectively the different values of the hundreds, tens and units digits of the subscribers line numbers.

Each of the forty output leads from the generator I02 appears in an impulse producing device, such as a space discharge tube. These impulse devices, such as devices IE1, IE8, IE9, III III, H2, H3 and H4, respond to the voltages applied thereto from the generator IE2 and produce in their output circuits H5, H6, H1, H8, H9 I23, 25 and I22 momentary impulses of negative polarity. The forty impulse leads from these generating devices appear on the connecting frame I23. The phase generator I92 is energized from a suitable source of alternating current I24 of any desired frequency and produces voltages of the forty difierent phases for each cycle of the source I24. The generator I02 and the impulse devices I87, I68, etc., may be of any suitable type and design, such as those disclosed in the patents to W. H. T. Holden, No. 2,252,766, of August 19, 1941, and 2,235,815 of June 9, 1942,. and the application of W. H. T Holden, Serial No. 361,536, filed October 17, 1940.

Thus there appears on the forty terminals of the connecting frame I23 during each cycle of the source I24 impulses of forty successive phases, ten diiferent phases for each of the forty digital places of any subscribers number. These impulse supply leads are connected to the sleeve conductors of the subscribers lines through the gaps of space discharge tubes and in combinations of four, one from each of the four groups. whereby the impulses of the four different phases that are applied to the sleeve conductor of each line characterize the designation of that line. To this end each subscriber-s line is provided with an individual space discharge tube having four digit electrodes, representing the four digits of the line number, and a single common electrode. For example, subscribers line IE8 is provided with a discharge tube I25 having a common anode iZE, which is connected through the crossconnecting rack I27 to the sleeve conductor 28 of line IBI. The tube I25 is also provided with four cathodes I29, I32, I3I and I32 representing respectively the thousands, hundreds, tens and units digits of the number of line I68. These cathodes are connected by jumper wires to the terminals on the rack I23 corresponding to the four phases that represent the subscribers line number. Assuming that the number of line I00 is 4567. the thousands electrode I29 is connected to the terminal corresponding to impulse lead H5 which carries impulses of phase No. 4 in the thousands group. Similarly electrodes 639, I3! and I32 are connected to terminals on the rack I23 corresponding to impulse leads H8, I26 and IE2 which carry impulses respectively of phase No. 5 in the hundreds group, phase No. 6 in the tens group, and phase No. 7 in the units group.

Subscriber's line I JI is also provided with an individual discharge tube I33 having a common anode I34 connected to the sleeve conductor I35 of line IHI. Tube I33 also has four digital electrodes which are connected through the rack 22 to the impulse leads on which appear the impulses of the four phases representing the number of line IOI. An inspection of the connections between the digit electrodes of tube I33 and the rack I23 will show that the number of line Ifll is 9332. Similarly, each of the other subscribers lines in the ofiice, of which there may be a total of ten thousand lines, is provided with one of these space discharge tubes, and all of these tubes are wired through rack I23 to the appropriate impulse leads.

The central office register sender 380 is equipped with an impulse receivin relay 30L which responds to the calling subscriber's dial, and

with the usual code and numerical registers 302 on which the oflice code designation and the number of the called line are registered as a result of the dialing operation. The sender is also provided with the usual control equipment whereby it cooperates with the originating marker 28'! to cause the operation of the district and office switches 234 and 2I0 to select an outgoing trunk 2II together with the appropriate impulse sending mechanisms for transferring the numerical designation and any other necessary information to controlling mechanisms beyond. The sender 330 also serves to receive the calling line identification signals and to transfer them to the identification mechanism disclosed in Fig. 4 of the drawings. To this end a connector 333 is provided whereby the sender 330 at the proper time seizes an idle one of the identifying mechanisms, in case more than one of these mechanisms is provided,

The line identifying mechanism of Fig. 4,-

which is seized by the sender 30!] when the time arrives for identifying the calling line, includes a series of forty discharge tubes 430, 4!", 492, 403, etc. These receiving identifying tubes respond to the impulses transmitted from the sending equipment in Fig. 1 associated with the calling subscribers line; they also respond to impulses of varying phases produced locally in the receiving equipment. These local impulses are generated by a series of forty impulse generating devices 404, 405, 436, 401, etc. The alternating currents of the forty different phases for energizing the impulse devices 4M, 435, 405, 437, etc., are supplied by the four groups of supply circuits 408, 439, M6 and 4| I, and these four groups of circuits are supplied with voltages of forty different phases by the generator M2. The forty difierent phases produced in the supply groups 408, 469, 413 and 4H are the same as those produced in the groups I33, I34, H35 and I36 at the transmitting end, and the source H3 is of the same frequency as the source I24. If desirable a single source of alternating current may be used to energize thegenerators I02 and M2. Th im- :7.

pulse generating tubes 404, 445, 4116, 431, etc., are of the same type as tubes I31, I38, I09, etc., except that they are designed to produce momentary impulses of positive polarity. Theoutput circuits of the ten impulse generating tubes 434,

etc., pertaining to the thousands group 438 are connected respectively to electrodes of ten receiving tubes 43!]. Similarly the output circuits of the impulse enerating tubes of the remaining three groups are connected respectively to the a" electrodes of the corresponding three groups of ten receiving tubes 43!, 4M and 433. For example, the output circuit of the generating tube 404 is connected to the control electrode 48 4 of the tube 463 in the thousands group, the output circuit of tube 435 is connected to the control electrode M5 of tube 4llI in the hundreds group, and the output circuits of generating tubes 4% and 437 are connected respectively to the'control electrodes 4H) and M! of tubes 402 and 403 of the tens and units groups.

The signal conductor 4i 8, over which the identifying signals are transmitted from the sender 343, includes an amplifier AIS, if desirable, for

amplifying these signals, This signaling con-' ductor 4I3 after leaving the amplifier M9 is connected in multiple to the control electrodes of all forty of the receiving tubes 489, 45H, 462, 403, etc. For instance the conductor 4! is connected through resistor 423 to the control eleci3 trode 42I of the tube 400 in the thousands group, through the resistor 422 to the control electrode 423 of the tube 40I in the hundreds group, through the resistor 424 to the control electrode 425 of the tube 402 in the tens group and through resistor 426 to the control electrode 421 of the tube 403 in the units group. Thus all of the identifying signals incoming over the signaling conductor 4I8 are applied simultaneously to all of the receiving tubes. Since the voltages produced in the forty supply circuits 468, 403, 4H) and 4i I are in phase with the corresponding voltages produced in the forty supply circuits I63, I34, I45 and I06 at the sending end, the forty successive impulses applied to the electrodes of tubes 4%, 4:, 402, 443, etc., are in phase respectively with the forty impulses produced in the impulse circuits of generating tubes I01, I08, I39, etc., at the sending end for each cycle of the alternating voltage. It follows, therefore, that if any particular combination of four generating tubes I01, I38, I09, III], etc., are connected to the sleeve conductor of the line and this sleeve conductor is extended through the sender 334 to the signaling conductor 4I3 associated with the forty receiving or indicating tubes 4%, 4M, 432, etc., the corresponding four receiving tubes will have impulses applied simultaneously to their control electrodes. Since the impulses transmitted over the signaling conductor 4I8' are negative in polarity and the impulses produced by the generating tubes 4B4, 4G5, 436, etc., are positive in polarity, the simultaneous application of a positive and a negative impulse to the control electrodes of a receiving tube 4% produces sufiicient voltage acrossthese electrodes to ionize the tube. Hence the four receiving tubes which correspond to the four generating tubes connected to the sleeve conductor through the medium of one of the individual line tubes I25 are ionized and cause the operation of their associated indicating relays 428, 429, 430 and 43,I to identify the digital characters of the subscribers line.

The anode circuits of the receiving tubes 4%, 4ilI, etc., include transformer windings which serve to impress alternating voltages upon the anode circuits for the purpose of quenching the tubes after they have performed their functions. For example, the anode circuit of the tube 469 may be traced from positive pole of battery through the winding of transformer 432, winding of relay 428, anode 433, cathode 434 to ground. For a more complete description of the manner in which these receiving tubes are operated and released, reference is made to the above-noted patent to W. H. T. Holden No. 2,252,766.

To further describe the detailed operation of the indicating system disclosed herein, it will be assumed that the subscriber of line It!) wishes to make a call requiring the preparation of a ticket indicating the charges assessed against the subscriber for the conversation. The call is initiated in the usual manner, and the line switches 353 and 232 operate to extend the calling line to the idle trunk 233. Also the sender selector switch 285 operates automatically to extend the calling line by way of trunk 283 to an idle register sender 333. When the sender is seized by the sender selector 205, a circuit is completed through the windings of the impulse relay 36! thence over the tip' and ring conductors through the sender selector 2115 through the line switches 282 and 290 to the subscribers line I06. Also the control relay 304 operates and closes a circuit from ground through its front contacts, normal contacts of relay 335, conductor 396 through the sender selector 295, conductor 2I2 thence to the sleeve conductor 2I3 of the trunk 2G3 through the contacts of switch 202, sleeve conductor 2M of link 26L contacts of switch 203 to the sleeve conductor I28 of the subscribers line I60. The application of ground potential to the sleeve conductor serves to hold the connection under the control of the register sender 306.

Dial tone is transmitted to the calling subscriber in the well-known manner, and he proceeds to manipulate his dial l35 to transmit se ries of impulses representing the office code and numerical designations of the wanted subscribers line. The impulse relay 3M responds to these impulses and operates the registers 302 of the sender to register the successive digits of the designation.

After the sender has received a number of the digits it seizes an idle marker 201 through a marl er-connector 206, and the office code designation is transferred to the marker. Thereafter the marker proceeds to test the trunks of the desired group, to select an idle trunk 2II therein, and to associate itself through frame connectors 5&8 and 209 with district and office switches 204 and 2H) for the purpose of operating these switches to extend the trunk 283 to the chosen idle trunk H I.

At some convenient time following the seizure of the sender 303 the control relay 30! is operated to close a circuit for operating the connector magnet 3&3. Magnet 389 is also operated thus completing the connection from the sender 303 to the identification mechanism shown in Fig. 4.

It will be noted that a connection has been completed from the sleeve conductor I28 of the subscribers line I69 through to the register sendor 388. However, this sleeve circuit is completely isolated from the impulse generator I02 by means of the space discharge tube I25, which is in a deionized condition. Thus, although voltage impulses are constantly being applied to the digit conductors I29, I39, ISI and I32, they are not transmitted over the sleeve circuit to the sender sinc the voltage of these impulses is not sufiicient to cause the ionization of the gap between these digit electrodes and the common anode I26.

Accordingly no impulses are transmitted to iden tify the calling line until the subscriber has completed the dialing of the first digit. At that time relay 3H associated with the first register operates, and a circuit is closed from battery through the winding of relay 395, contacts of relay 3I0,

normal contacts of relay 3 to ground. Relay s05 operates and modifies the sleeve signaling circuit so that it now leads through the front contacts of relay 396, primary winding of transformer 3I2, resistance lamp 3I3 to the positive pole of battery 3M. The positive potential of the battery 314 on th sleeve conductor serves to continue the holding condition of the switches 290 and 283 and for the sender selector switch 235. Furthermore, the potential of battery 3I4 applied to the anode I26 of the tube I25. Therefore, each time thereafter that a negative impulse is applied to the electrodes I29, I30, I3I and I32, the tube I25 ionizes, and these impulses are transmitted over the sleeve signaling circuit through the primary winding of the transformer 3 I 2. Accordingly impulses of the same phase and direction are induced in the secondary winding of the transformer 3I2 and are transmitted over conductor 3I5 through connector 303, conductor M3 and in multiple to the control electrodes of all forty tubes 4G0, GBI, etc. Since the impulses transmitted over this signaling circuit from the digit electrode I29 of the tube I25 are of the No. 4 phase, they are impressed simultaneously on the tube 463 with impulses of like phase from the impulse generating tube @5 1. Accordingly the single tube 463 ionizes, and current flows in the main anode-cathode discharge circuit causing the operation of the slow-release relay 428. Relay 428 applies ground potential to conductor 435 to cause the operation of the register 438 to register the thousands digit 4. Since the impulses transmitted over the signaling circuit from the hundreds digit electrode I30 are of phase N0. 6 in the hundreds group, these impulses are impressed simultaneously upon the single tube MI with impulses of the same phase from the generating device 4B5. Accordingly tube ifil operates to the exclusion of all other tubes in response to these impulses, and relay 429 is energized to cause the registration of the hundreds digit 5 in the register 436. In like manner the impulses transmitted from the electrodes I3I and I32, of phases No. 6 and No. 7 of the tens and units groups, respectively, cause the operation of tubes i-GZ and M3. The operation of these tubes results in the energization of relays 63B and 31, which cause the registration respectively of the tens and units digits 6 and '7 in the register 436.

After the called subscribers line has been fully registered in the register 332 of the sender 390, this registration is transferred through the connector 393 to a called line register 43'! in the mechanism of Fig. 4. Also at some suitable time the control relay 3 is operated to release relay 305, thus disconnecting the sleeve signaling circuit from the transformer 3 i2 and restoring it to the ground connection at the front contact of relay 3%. The disconnection of the battery 3M from the sleeve conductor I28 causes the tube I25 to cease discharging in response to the impulses from the impulse generator I24. Thus the generator is again completely isolated from the conductors of the calling subscriber's line, and no interference can take place with conversation on this line or with conversations occurring on adjacent lines.

At the proper time in the progress of the connection being established the marker 291 and the sender 309 are released, and the connection is held in the usual manner under the control of the subscribers station.

The designations of the calling and called lines are now registered on the registers 436 and 431. These registrations may now be used to control the operation of a printing mechanism 438 to print a ticket for charging the call against the calling subscriber. If desirable, the printer mechanism may also be controlled in the wellknown manner to measure the time during which conversation is ensuing to assess the charge on the basis of the duration of the call as well as its destination.

Although the invention has been illustrated as applied to an automatic system in which the numbers of the subscribers lines are identified for the purpose of preparing message tickets, it will be understood that it may also be used for identifying the numbers of lines at operators positions or for other purposes.

The automatic switches illustrated herein are assumed to be switches of the crossbar type although it is obvious that any type of switch may be used for extending the subscribers lines. For

a full understanding of the operation of the system in which crossbar switches are employed together with register senders and switch-controlling markers, reference may be made to the patent to Carpenter, No. 2,235,803 of March 18, 1941.

What is claimed is:

1. In a signaling system, a plurality of lines each of which has an identifying designation, means for generating a multiplicity of signal impulses of different characters, connecting means including space discharge devices between said generating means and said lines for applying to each line a plurality of said signal impulses in a combination of characters representing the line designation, a circuit for transmitting the impulses pertaining to a particular one of said lines, and means for receiving andutilizing the transmitted impulses to identify said particular line.

2. In a signaling system, a plurality of lines each of which has an identifying designation, each line having a signal transmitting conductor, a plurality of multielectrode discharge tubes, one for each line, each of said tubes having one of its electrodes connected to the transmitting conductor of the associated line, means for generating signal impulses of a, multiplicity of different phases, connecting means for applying to a plurality of the electrodes of any one of said tubes impulses from said generator in a combination of phases representing the designation of the associated line, said impulses causing the discharge of said tube and the transmission of signals over the transmitting conductor of said line, and means for receiving and utilizing the transmitted signals to identify said line.

3. In a signaling system, a plurality of'lines, each line having a signal transmitting conductor, a plurality of multielectrode discharge tubes, one for each line, each of said tubes having one of its electrodes connected to the transmitting conductor of the associated line, means for extending a connection including a particular one of said lines and for establishing a signaling circuit including the signal transmitting conductor of said line, means for generating signal impulses of a multiplicity of difierent phases, connecting means for impressing a combination of said phase impulses representing the designation of said particular line upon the electrodes of the tube associated with said line to cause the discharge of said tube and the transmission of corresponding signals over said signaling circuit, and means for receiving and utilizing the signals transmitted over said circuit to identify the designation of said particular line.

4. In a signaling system, lines each having a difierent designation, each of said lines having a signal transmitting conductor, a plurality of discharge tubes, one for each line, each tube having a plurality of digit electrodes representing respectively the digital places of the line designation and also having a common electrode connected to the transmitting conductor of the associated line, means for generating a multiplicity of impulses of different characters, connecting means for applying impulses of a combination of characters representing the designation of a particular line to the digit electrodes of the associated discharge tube, said impulses causing the discharge of said tube and the transmission of signals over the transmitting conductor of said line, and means for receiving and utilizing the transmitted signals to identify the designation of said line.

5. In a signaling system, lines each having a difierent designation, each of said lines having a signal transmitting conductor, a plurality of discharge tubes, one for each line, each tube having a plurality of digit electrodes representing respectively the digital places of the line designation and also having a common electrode connected to the transmitting conductor of the associatedline, means for generating impulses of a multiplicity of difierent phases, circuit connections between said generating means and said tubes for impressing upon the digit electrodes of each tube impulses in a combination of phases selected to represent the designation of the associated line, means for altering the potential of the common electrode of the tube associated with any particular line to cause the discharge of said tube and the transmission over the transmitting conductor of said line of signal impulses of the corresponding phases, and means for re ceiving the transmitted impulses and for utilizing them to identify the designation of said particular line.

6. In a signaling system, a plurality of lines each having an identifying designation, each line having a signal transmitting conductor, automatic switches, a common register sender responsive to impulses transmitted over any one of said lines for controlling the operation of said switches to establish a connection, means for extending a particular one of said lines to said register sender, discharge tubes, one for each of said lines, each of said tubes having as many digit electrodes as there are digital places in the designation of the associated line and having a common electrode connected to the transmitting conductor of the associated line, generating means for producing impulses of a multiplicity of different phases, connecting means between said generating means and said tubes for applying to the digit electrodes of each tube impulses in a'combination of phases characterizing the designation of the associated line, means in the register sender for closing a signaling circuit includingthe signal transmitting conductor of said particular line, the closure of said circuit causing the discharge of the associated tube and the transmission over said signaling circuit of impulses of corresponding phases, and means responsive to the impulses transmitted over said signaling circuit for identifying the designation of said particular line.

'7. In a signaling system, a plurality of lines each of which has an identifying designation, each line having a signal transmitting conductor, a plurality of multielectrode discharge tubes,

each of said tubes having one of its electrodesconnected to the transmitting conductor of one of said lines, means for generating signal impulses of a multiplicity of difl'erent phases, connecting means for applying to a plurality of the electrodes of any one of said tubes impulses from said generator in a combination of phases representing the designation of the associated line, said impulses causing the discharge of said tube and the transmission of signals over the transmitting conductor of said line, and a receiving mechanism comprising a plurality of discharge tubes selectively responsive to saidtransmitted signals for identifying the designation of said line.

8. In a signaling system, a plurality of lines each of Which has an identifying designation, each line having a signal transmitting conductor, a plurality of multielectrode discharge tubes, one for each line, each of said tubes having one of its electrodes connected to the transmitting conductor of the associated line, means for generating signal impulses of a multiplicity of different phases, connecting means for applying to a plurality of the electrodes of any one of said tubes impulses from said generator in a combination of phases representing the designation of the associated line, said impulses causing the discharge of said tube and the transmission of signals over the transmitting conductor of said line, a receiving mechanism comprising a plurality of discharge tubes, a second impulse generating means for generating impulses of difierent phases and applying them to the electrodes of said receiving tubes, and means for applying to the electrodes of said receiving tubes the impulses transmitted over the transmitting conductor of said line to selectively operate said re-- ceiving tubes.

9. In a signaling system, a plurality of lines each ,having an identifying designation, an impulse transmitter at the substation of each of said lines, each line having a signal transmitting conductor, automatic switches, a common register sender responsive to impulses transmitted by the substation transmitter of any of said lines for controlling the operation of said switches to establish a connection, means for extending a particular one of said lines to said register sender, discharge tubes, one for each of said in a combination of phases characterizing the designation of the associated line, means in the register sender responsive to the impulses transmitted from the substation transmitter of said particular line for closing a signaling circuit including the signal transmitting conductor of said particular line, the closure of said circuit causing the discharge of the associated tube and the transmission over said signaling circuit of impulses of corresponding phases, and means responsive to the impulses transmitted over said signaling circuit for identifying the designation of said particular line.

10. The combination with a plurality of lines each having an identifying designation of an impulse transmitter for each of said lines, each line having a signal transmitting conductor, automatic switches, a common register sender responsive to successive series of impulses sent over any calling one of said lines by the impulse transmitter thereof to register the designation of a desired line, said sender serving to control the operation of said automatic switches in accordance with the registered designation to establish the desired connection, means for extending the calling one of said lines to said register sender, discharge tubes, one for each of said lines, each of said tubes having as many digit electrodes as there are digital places in the designation of the associated line and having a common electrode connected to the transmitting conductor of the associated line, generating means for producing impulses of a multiplicity of different phases, connecting means for applying to the digit electrodes of each tube impulses in a combination of phases characterizing the designation of the associated line, means in said register sender responsive to any particular one of the series of impulses transmitted thereto over said calling line for closing a signaling circuit including the signal transmitting conductor of said calling line, the closure of said circuit causing the discharge of the associated tube and the transmission over said signaling circuit of impulses of corresponding phases, and means responsive to the impulses transmitted over said signaling circuit for identifying the designation of said calling line.

WILLIAM H. T. HOLDEN. 

